The aim of this project is to develop an immunofluorescent assay system capable of quantitating the secretion of cytokines by individual cells in mixed cell populations by encapsulating individual cells in agarose gel microdrops (GMD) and then measuring secretion of cytokine molecules after appropriate stimulation. The combination of immunofluorescent staining of secreted cytokines and cell surface labeling techniques will permit simultaneous determination of the phenotype of cytokine-secreting cells by using two or three-color flow cytometric analysis. the availability of this assay system could become an important tool for basic research, clinical diagnostic and industrial applications. PROPOSED COMMERCIAL APPLICATION: The majority of commercialized biotechnology products are cytokines. In addition the cytokine research product market is in excess of $500 M. New assay formats for quantitating cytokine secretion at the single cell level would also impact clinical diagnostic research.